1. Field of the Invention
The present invention relates to a base plate, a base unit, a motor, a disk drive apparatus, and a method of manufacturing the base plate.
2. Description of the Related Art
Hitherto, a disk drive apparatus such as a hard disk drive has been known. A motor for rotating a disk is mounted in the disk drive apparatus. The conventional disk drive apparatus is disclosed, for example, in Japanese Patent Application Publication No. 2012-005339. The disk drive apparatus includes a base that supports all the components of the motor (see paragraph 0031 and FIG. 1 of Japanese Patent Application Publication No. 2012-005339).
In recent years, the demand for thin notebook PCs or tablet PCs has been increased. Accordingly, it is also necessary to make a disk drive apparatus mounted in such a PC thinner than the past. In order to make the disk drive apparatus thin, it is preferable to reduce the axial thickness of a base plate that supports the motor. In particular, motor components such a stator and a hub should be arranged around a central axis of the motor. Thus, it is preferably to particularly reduce the axial thickness of the base plate in a lower side of the motor components.
However, if the axial thickness of the base plate is reduced, the stiffness of the base plate is weakened. If the stiffness of the base plate is weakened, vibration and noise due to driving of the motor are increased. Further, the position of the disk becomes unstable, and errors in reading and writing of data easily occur.